Atomic layer deposition and conversion

ABSTRACT

A method for growing films for use in integrated circuits using atomic layer deposition and a subsequent converting step is described. In an embodiment, the subsequent converting step includes oxidizing a metal atomic layer to form a metal oxide layer. The atomic layer deposition and oxidation step are then repeated to produce a metal oxide layer having sufficient thickness for use as a metal oxide layer in an integrated circuit. The subsequent converting step, in an embodiment, includes converting the atomic deposition layer by exposing it to one of nitrogen to form a nitride layer, carbon to form a carbide layer, boron to form a boride layer, and fluorine to form a fluoride layer. Systems and devices for performing the method, semiconductor devices so produced, and machine readable media containing the method are also described.

This application is a Divisional of U.S. application Ser. No.10/137,058, filed May 2, 2002 which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to deposition techniques and, moreparticularly, to deposition techniques for forming thin films on wafersor substrates and then converting the films into a different anothercomposition.

BACKGROUND OF THE INVENTION

Integrated circuits (IC) are often fabricated with one or moresemiconductor devices, which may include diodes, capacitors, anddifferent varieties of transistors. These devices are generallyfabricated by creating thin films of various materials, e.g. metals,semiconductors or insulators, upon a substrate or semiconductor wafer.Wafer and substrate are used interchangeably to refer to semiconductorstructures during processing, and may include other layers that havebeen fabricated thereon. The physical characteristics and tightlycontrolled placement of films on a substrate will define the performanceof the semiconductor device and its surrounding circuitry. Manysemiconductor devices require a dielectric layer that must be reliable.Specifically, the dielectric layer must be essentially free from defectsthat cause shorting through the dielectric layer. Oxides and nitridesare used to form dielectric layers in semiconductor devices.

One process for forming metal oxide thin films on semiconductor wafersis chemical vapor deposition (“CVD”). CVD is used to form a thin film ofa desired material from a reaction of vapor-phase chemicals containingthe chemical constituents of the material. CVD processes operate byconfining one or more semiconductor wafers in a reaction chamber. Thechamber is filled with one or more gases that surround the wafer. Thegases for the deposition of metal oxides includes a metal precursor anda reactant gas, e.g. water vapor, to be introduced into the chamber atthe same time. Energy is supplied within the chamber and particularly tothe reactant gases near the wafer surface. A typical energy is heatapplied to the substrate. The energy activates the reactant gaschemistry to deposit a film from the gases onto the heated substrate.Such chemical vapor deposition of a solid onto a surface involves aheterogeneous surface reaction of the gaseous species that adsorb ontothe surface. The rate of film growth and the quality of the film dependon the process conditions. Unfortunately, the metal precursor and thereactant gas also react during the gas phase remote from the substrate.Such a gas phase reaction produces contaminants and/or involve asignificant quantity of precursor so that an insufficient amount isavailable for deposition on the substrate. As a result, the gas phasereaction may become dominant and the thin film coverage is poor. Thatis, pinholes may be formed in the resulting metal oxide layer. Moreover,using water (H₂O) gas as the reactant gas results in impurities, such ashydroxide (OH), remaining in the resulting metal oxide layer.

Semiconductor fabrication continues to advance, requiring finerdimensional tolerances and control. Modem integrated circuit design hasadvanced to the point where line width may be 0.25 microns or less. As aresult, repeatability and uniformity of processes and their results isbecoming increasingly important. Generally, it is desired to have thinfilms deposited on the wafer to save space. Yet reducing the thicknessof films can result in pinholes and in less mechanical strength.

Another development in the field of thin film technology for coatingsubstrates is atomic layer deposition (ALD). A description of ALD is setforth in U.S. Pat. No. 5,879,459, which is herein incorporated byreference in its entirety. ALD operates by confining a wafer in areaction chamber at a typical temperature of less than 300 degrees C.Precursor gas is pulsed into the chamber, wherein the pulsed precursorforms a monolayer on the substrate by chemisorption. The low temperaturelimits the bonding of the precursor to chemisorption, thus only a singlelayer, usually only one atom or molecule thick, is grown on the wafer.Each pulse is separated by a purge pulse which completely purges all ofthe precursor gas from the chamber before the next pulse of precursorgas begins. Each injection of precursor gas provides a new single atomiclayer on the previously deposited layers to form a layer of film.Obviously, this significantly increases the time it takes to depose alayer having adequate thickness on the substrate. As a numericalexample, ALD has a typical deposition rate of about 100 Å/min and CVDhas a typical deposition rate of about 1000 Å/min. For at least thisreason, ALD has not met with widespread commercial acceptance.

In light of the foregoing, there is a need for fabrication of thin filmswhich are thinner and have a reduced number of defects.

SUMMARY OF THE INVENTION

The above mentioned problems with thin film fabrication techniques areaddressed by the present invention and will be understood by reading andstudying the following specification. Systems and methods are providedfor fabricating thin films on substrates. The fabrication technique ofthe present invention grows a thin film by atomic layer deposition andthen converts the film to produce a thin film having a differentcomposition than the ALD deposited film. In an embodiment, each ALD thinfilm is converted before a subsequent ALD film is deposited. In oneembodiment of the invention, a metal film is deposited by ALD. The metalfilm is then oxidized to produce a metal oxide film. In an embodiment,the metal is aluminum. In an embodiment, the metal is titanium. In anembodiment, the metal is tantalum.

In an embodiment, the thin film formed by atomic layer deposition isconverted from an essentially pure metal film to a compound film thatincludes the metal and at least one second element. In an embodiment,the second element is oxygen. In an embodiment, the compound film is anoxide. In an embodiment, the second element is nitrogen. In anembodiment, the compound film is a nitride. In an embodiment, the secondelement is boron. In an embodiment, the compound film is a boride. In anembodiment, the second element is carbon. In an embodiment, the compoundfilm is a carbide. In an embodiment, the second element is fluorine. Inan embodiment, the compound film is a fluoride.

In an embodiment, a laminate or compound layer having at least twocompounds in the layer is formed. The first element layer is depositedby ALD. This layer is then converted to a compound. A second elementlayer is deposited by ALD. This layer is then converted to a compound.In an embodiment, both the first and second elements are deposited byALD and then both elements are converted. In an embodiment, one of thefirst element layer and second element layer is deposited by ALD and notconverted. If the one layer includes a compound, then it is deposited byALD in its compound form. The other of the first element layer and thesecond element layer is converted.

Additional embodiments of the invention include deposition devices andsystems for forming metal oxide films on substrates, and machinereadable media having fabrication instructions stored thereon, allaccording to the teachings of the present invention as described herein.

These and other embodiments, aspects, advantages, and features of thepresent invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of the deposition process of an embodiment of theinvention.

FIG. 2A is a flowchart of the deposition process of an embodiment of theinvention.

FIG. 2B is a time graph of a deposition process of the presentinvention.

FIG. 3 is a view of a thin film of the present invention as a dielectriclayer in a capacitor and as a gate layer in a transistor.

FIG. 4 is a view of a reactor for use with the process of the presentinvention.

FIG. 5 is a view of a reactor system for use with the process of thepresent invention.

FIG. 6 is a view of a memory system containing a semiconductor devicehaving a thin film according to the present invention.

FIG. 7 is a view of a wafer containing semiconductor dies, each having asemiconductor device with a thin film of the present invention.

FIG. 8 is a block diagram of a circuit module that has a semiconductordevice with a thin film of the present invention.

FIG. 9 is a block diagram of a memory module that has a semiconductordevice with a thin film of the present invention.

FIG. 10 is a block diagram of an electronic system that has asemiconductor device with a thin film of the present invention.

FIG. 11 is a block diagram of a memory system that has a semiconductordevice with a thin film of the present invention.

FIG. 12 is a block diagram of a computer system that has a semiconductordevice with a thin film of the present invention.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the invention, reference ismade to the accompanying drawings which form a part hereof, and in whichis shown, by way of illustration, specific embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,and electrical changes may be made without departing from the scope ofthe present invention. The terms wafer and substrate used in thefollowing description include any structure having an exposed surfaceonto which a layer is deposited according to the present invention, forexample to form the integrated circuit (IC) structure. The termsubstrate is understood to include semiconductor wafers. The termsubstrate is also used to refer to semiconductor structures duringprocessing, and may include other layers that have been fabricatedthereupon. Both wafer and substrate include doped and undopedsemiconductors, epitaxial semiconductor layers supported by a basesemiconductor or insulator, as well as other semiconductor structureswell known to one skilled in the art. The term conductor is understoodto include semiconductors, and the term insulator is defined to includeany material that is less electrically conductive than the materialsreferred to as conductors. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims, along with thefull scope of equivalents to which such claims are entitled.

According to the teachings of the present invention, fabrication offilms on substrates, devices and systems for such fabrication, mediacontaining instructions therefor, and integrated circuits producedaccording to the present invention are described.

The use, construction and fundamental operation of reactors fordeposition of films are understood by those of ordinary skill in the artof semiconductor fabrication. The present invention may be practiced ona variety of such reactors without undue experimentation. Furthermore,one of ordinary skill in the art will comprehend the necessarydetection, measurement, and control techniques in the art ofsemiconductor fabrication as well as the more inclusive art ofindustrial processing for producing films on substrates upon reading thedisclosure.

It will be understood that the terms “precursor” and “reactant” are usedherein to differentiate between a chemical compound that includes ametal component to be deposited on a substrate and a gas which reactswith the compound to deposit the metal component on a wafer. Thisnomenclature is used herein as a tool to clearly describe the inventionas both the “precursor” and the “reactant” chemically react with eachother to form the desired film on the substrate. Accordingly, the term“precursor” is not intended to imply a time relationship with the“reactant” unless explicitly described.

Applicant hereby incorporates by reference copending U.S. patentapplication Ser. No. 09/782,207, which is assigned to the assignee ofthe present application.

FIG. 1 depicts an atomic layer deposition (ALD) process according to theteachings of the present invention. A substrate is prepared to receive acompound layer, step 15. This includes forming required layers,trenches, oxides such as field oxides and other structures on the basesurface of a wafer. In an embodiment, the compound layer is a metalnitride. In an embodiment, the compound layer is a carbide. In anembodiment, the compound layer is a boride. In an embodiment, thecompound layer is a fluoride. When depositing a dielectric layer for acapacitor, a field insulator is formed on the wafer. The field insulatoris etched to form a trench. A bottom electrode layer is deposited in thetrench. Thereafter, the dielectric layer, e.g., metal oxide or metalnitride, is deposited on the bottom electrode layer according to theteachings of the present invention. After the dielectric is formed a topelectrode layer is deposited on the dielectric layer. The remainingstructure for the integrated circuit is then formed. When depositing agate oxide for a transistor, the source and drain are formed in thesubstrate. A gate insulator, e.g., metal oxide, layer is formed on thesubstrate intermediate the source and drain according to the teachingsof the present invention. Thereafter, the gate is formed on the gateinsulator. The remaining structure for the integrated circuit is thenformed. Step 17 is the first step in the ALD process. A first gas flowsinto a reaction chamber containing the substrate. The first gas isdeposited at the surface of the substrate. The first gas includes afirst element that forms part of the desired compound. In an embodiment,the first gas includes titanium. In an embodiment, the titanium is aTiCl₄ gas. In an embodiment, the first gas includes tantalum. In anembodiment, the tantalum is a TaCl₅ gas. In an embodiment, the first gasincludes aluminum. In an embodiment, the aluminum is a trimethylaluminum(TMA) gas. A second gas flows into the chamber containing the substrateand first gas, step 19. The second gas is deposited at the surface ofthe substrate. The second gas includes a reactant element that willreact with the first gas to deposit a first-element containing layer onthe substrate. In an embodiment, the second gas is activated hydrogen.In an embodiment, the second gas is not H₂O. The first and second gasesare reacted in an ALD reaction to form a monolayer of metal film, step21, in an embodiment. In this embodiment of ALD, the monolayer of metalfilm formed by the first and second gases is only about one molecule inthickness. The monolayer is an essentially pure layer of the firstelement. Essentially pure is defined as greater than 99% pure. In a moredesirable embodiment, essentially pure is greater than 99.9% pure, plusor minus about 0.1%. In an even more desirable embodiment, essentiallypure is greater than 99.99% pure, plus or minus 0.01%. In anotherembodiment of ALD, the first and second gases react to form a layer thatis greater than a monolayer. After the ALD layer is formed on thesubstrate, the ALD layer is exposed to a reacting gas, step 23. Thereacting gas converts the ALD layer containing the first element into acompound containing the first element and at least a second element fromthe reacting gas. In an embodiment, the reacting gas includes oxygen. Inan embodiment, the oxidizing gas is dioxide (O₂). In an embodiment, theoxidizing gas is ozone (O₃). In an embodiment, the oxidizing gas isnitrogen oxide (N₂O). In an embodiment, the oxidizing gas is activatedoxide (O*). When the metal monolayer is titanium, then the oxidizing gasconverts the titanium monolayer to ATiO₃, where A denotes Ba or Sr orboth. When the metal monolayer is tantalum, then the oxidizing gasconverts the tantalum monolayer to Ta₂O₅. When the metal monolayer isaluminum, then the oxidizing gas converts the aluminum monolayer tolumina (Al₂O₃). The process is repeated, step 25, until the desiredthickness of the final layer of the first and second elements is formed.The process returns to step 17 to begin forming another ALD layer ormonolayer of a first element, which is then converted, according to theteachings of the present invention. In an embodiment, the first elementis a metal and the second element is oxygen. After the final layer hasthe desired thickness, then additional integrated circuit fabricationprocesses are performed on the substrate as needed, step 27.

FIG. 1 also shows an embodiment of the present invention in broken line.Steps 15, 17, 19 and 21 are the same as described above. This embodimentrepeats the ALD steps 17, 19, 21 until the ALD layer has the final,desired thickness, step 31. Thereafter, the ALD deposited layer isconverted, step 33. In an embodiment, converting includes reacting theALD layer with at least one second element to transform the ALD layer(single element layer) into a compound layer (multiple element layer).In an embodiment, reacting is oxidizing. In an embodiment, the firstelement is a metal. The process then proceeds, if needed, to step 27.

FIG. 2A shows an ALD process 200 according to the teachings of thepresent invention. ALD process 200, in the illustrated embodiment,begins by initiating an inert purge gas flow through a reactor (210).The purge gas maintains the chamber at a generally constant pressure. Inone embodiment of the present invention the purge gas flow is pulsed,for example only injecting purge gas between other gas pulses. Inanother embodiment, purge gas is not used at all, i.e. step 210 is notperformed.

The precursor gas containing a first element, e.g., metal, to bedeposited on the substrate now flows into the reaction chamber (212).The metals include, for example, titanium, tantalum, or aluminum. Themetals can also include alloys of these metals or other metal that oneof ordinary skill would deposit on a substrate. The precursor gas flowcontinues until a volume closely adjacent the surface of the substrateon which the metal will be deposited is saturated by the precursor gas(214). According to the teachings of the present invention, theprecursor gas saturates the topology of the substrate so that adequateprecursor material is adjacent the substrate surface by the precursorgas entering and filling the steps, trenches, and holes. One of ordinaryskill will understand the same upon reading the disclosure. Theprecursor gas flow, as well as purge gas flow if present, continuesuntil the required saturation occurs depending on the processingconditions dictated by the type of substrate and precursor gas, and thetopology of the substrate (216). A substrate having numerous or highaspect steps may require a longer precursor gas flow period than asubstrate which has few steps or relative low aspect steps

Precursor gas flow ends once the precursor gas saturates adjacent thesubstrate according to the processing conditions of the presentdeposition (218). After or substantially at the same time precursor gasflow is stopped, reactant gas flow (for example, activated hydrogen)begins in the reaction chamber (220). Reactant gas continues to flowinto the reaction chamber until the reactant gas saturates the volumeadjacent the surface of the substrate on which the substance in theprecursor gas will be deposited (222). The precursor gas and thereactant gas chemically react and deposit the desired material in a ALDlayer, e.g., monolayer, on the substrate. In an embodiment, thedeposited monolayer is about one atomic layer thick. In an embodiment,the deposited ALD layer is more than one atomic layer thick. Themonolayer and the ALD layer are an essentially pure layer of a singleelement.

The present process may continue the purge gas flow while the reactantgas flows into the reaction chamber (224). Once a sufficient quantity ofreaction gas is present to complete the reaction with the precursor todeposit a layer on the substrate, reaction gas flow ends (226). Purgegas flow may continue to partially flush the residual reaction andprecursor gases and the by-product gas of the precursor and reactantreaction from the reaction chamber. A converting gas flows into thereaction chamber (228). The converting gas includes an oxidizing gas.The oxidizing gas oxidizes the monolayer, which is a metal, to form adielectric layer. The oxidation continues until sufficient time haselapsed to oxidize essentially all of the metal monolayer (230). If themonolayer is not sufficiently oxidized the process continues flowing theoxidizing gas to the metal monolayer. Once the monolayer is sufficientlyconverted, e.g., oxidized, then the process proceeds to step 232. Atstep 232, it is determined if the converted layer formed by the previoussteps has the desired film thickness. If the converted formed by one ora plurality of the ALD and conversion steps of the present invention hasthe desired thickness, then the ALD and conversion process of thepresent invention ends. If purge gas is still flowing, then the purgegas flow ends (234) usually after the remnants of the precursor,reactant, and by-product gases are purged from the chamber. The processof the present invention terminates at box 236. The reader should notethat process termination may comprise initiation of further processingand does not necessarily require shutdown of the reactor, e.g. the abovesequence of steps can be repeated or additional fabrication steps areperformed. While one embodiment of the invention includes all of theabove steps, the present invention includes other embodiments which donot include all of the above steps.

If the desired thickness of the layer has not been achieved (222), thenthe process returns to step 210 or step 212 and begins another cycle.The process then reiterates the above sequence/process until step 232determines that the converted layer has the desired thickness.

One embodiment of the present inventive process is shown in FIG. 2B. Theprocess begins with the flow of an inert purge gas and a precursor gascontaining the first element into the reaction chamber. The precursorgas flows into the chamber until a sufficient quantity of the elementthat will form the monolayer is adjacent the substrate as determined bystoichiometry of the particular reaction needed to deposit the desiredfilm on the substrate. The precursor must include a certain minimumamount of the first element to be deposited on a wafer and otherreactive components that assist in the depositing the first element onthe wafer. The precursor may flow into the reactor in a quantity greaterthan determined by the stoichiometry of the reaction. In thisembodiment, the precursor gas flow ends followed by a short period ofonly purge gas flow. The reactant gas flows into the chamber until asufficient quantity of reactant gas is available to react with theprecursor at the surface of the substrate to deposit the desired firstelement film. An embodiment of the reactant gas include activated H.Like the precursor gas flow, the reactant gas and its flow reaches orexceeds the quantity that is determined by the stoichiometry of theparticular reaction. Thereafter, the reactant gas flow stops. After thereactant gas flow stops, the converting gas flows into the reactionchamber. In an embodiment, the converting gas is an oxidizing gas andthe first element monolayer is a metal. Accordingly, the metal monolayeron the substrate is oxidized. Thereafter, the flow of converting gasstops. This process is repeated until a converted film of a desiredthickness is deposited on the substrate.

The converting gas includes an activated element that reacts with theALD deposited layer. In an embodiment, the converting gas includes anactivated oxygen. In an embodiment, the converting gas includesactivated NH₃. In an embodiment, the converting gas includes activatedN₂O.

The amounts of the precursor gas, the reactant gas, or the convertinggas meets or exceeds the amount of material required by thestoichiometry of the particular reaction. That is, the amount ofprecursor, reactant, converting gas flow, in certain embodiments,provides excess mass in the reactor. The excess mass is provided toensure an adequate reaction at the surface of the wafer. In thisembodiment, the ratio of precursor, reactant, or converting componentsin the gas phase usually is different than the stoichiometry of thefilm.

FIG. 3 shows an integrated circuit 300 including a layer formedaccording to the teachings of the present invention. The layer is adielectric in a capacitor 302. The layer is a gate insulator in atransistor 304. It is within the scope of the present invention to formthe dielectric layer and gate insulator layer for both elements at thesame time. It is within the scope of the present invention to form thedielectric layer for the capacitor and the gate insulator layer for thetransistor at different times during fabrication. Capacitor 302 isformed on substrate 305. In an embodiment, a trench 307 is formed ininsulator layer 309. A bottom electrode layer 311 is formed in thetrench 307. A dielectric layer 313 is formed, according to the teachingsof the present invention, on the bottom electrode layer 311. A topelectrode layer 315 is formed on the dielectric layer 313. Thetransistor 304 is also formed on substrate 305. A field oxide 321 isformed on the substrate 305. The source and drain regions 323 and 325are doped into the substrate 305. A gate insulator, e.g. an oxide or anitride, layer 327 is formed according to the teachings of the presentinvention on the substrate 305 intermediate the source and drain regions323 and 325. A gate 329 is formed on the gate insulator layer 327.

Dielectric layer or gate insulator layer 313 or 327 is a metal oxidematerial having a composition that includes the form MOx. In oneembodiment, the metal component M is a refractory metal. In anembodiment, the refractory metal is tantalum (Ta). In an embodiment, therefractory metal is titanium (Ti). In an embodiment, the refractorymetal is tungsten (W). The refractory metals of chromium (Cr), cobalt(Co), hafnium (Hf), molybdenum (Mo), niobium (Nb), vanadium (V) andzirconium (Zr) are included in some embodiments. Benefits may be derivedby matching the metal oxide layer to the adjacent metal-containingelectrode. For example, the TaOx layer 313 or 327 can be grown on atantalum containing bottom electrode layer.

FIG. 4 depicts one embodiment of an atomic layer deposition (ALD)reactor 400 suitable for practicing the present invention. FIG. 4 isprovided for illustrative purposes and the invention may be practicedwith other reactors. The embodiment shown in FIG. 4 includes a chamber401 that is a pressure-sealed compartment for mounting a substrate 402on susceptor 407. Chamber 401 is typically manufactured from aluminumand is designed to contain a low-pressure environment around substrate402 as well as to contain process gases, exhaust gases, and heat orplasma energy within chamber 401. The illustrated substrate 402 includesa substrate base 402A on which are deposited first and second layers402B and 402C. Inlet gas manifold 403 supplies process gases, forexample precursor gases, reactant gases and converting gases, at acontrolled flow rates to substrate 402. A source of precursor gas 416 isconnected to manifold 403. A source of purge gas 417 is connected tomanifold 403. A source of reactant gas 418 is also connected to manifold403. A source of converting gas 419 is also connected to manifold 403.Carrier gases, such as helium, argon or nitrogen, may also be suppliedin conjunction with the gases supplied by the manifold as is known andunderstood by one of ordinary skill in the art. Chamber 401 alsoincorporates a pumping system (not shown) for exhausting spent gasesfrom chamber 401 through exhaust port 404.

ALD reactor 400 includes means for supplying energy to the reactableconstituents or compounds in the process gases in chamber 401 on thesurface of the substrate 402. The supplied energy causes the reactableconstituents to react or decompose and deposit a thin film onto an uppersurface of substrate 402. In one embodiment, the supplied energyincludes thermal energy supplied by heat lamps 406. In the illustratedexample, lamps 406 are positioned in the base of chamber 401. Heat lamps406 emit a significant amount of near-infra red radiation that passesthrough susceptor 407 to heat substrate 402. Alternatively, susceptor407 is heated by heat lamps 406 and substrate 402 is heated byconduction from susceptor 407. The heat lamps 406 may be placed atalternate locations according to the parameters of the specificdeposition process being performed according to the present invention.

Another embodiment supplies reaction energy by a radio frequency (RF)generator 408 as shown in FIG. 4. RF generator 408 creates a RF fieldbetween substrate 402 and an anode. In the embodiment shown in FIG. 4,susceptor 407 is grounded while the RF signal is applied to a processgas manifold 409. Alternative and equivalent ALD reactor designs will beunderstood by reading the disclosure. An RF anode may be providedseparately (not shown) and process gas manifold 409 may be electricallyisolated from the RF supply. For example, the RF signal is applied tosusceptor 407 and process gas manifold 409 is grounded.

In general, the energy sources 406 and 408 are intended to providesufficient reaction energy in a region near the surface of substrate 402to cause decomposition and/or reaction of the constituents of thepresent gas to deposit the first element, e.g., the metal species, inthe process gases onto a surface of the substrate. One of ordinary skillin the art will understand upon reading the disclosure that any one,combination, or equivalent of the above can be employed to provide thenecessary reaction energy.

One embodiment includes plasma reactors because these allow filmdeposition at lower temperatures and are used in the semiconductorindustry. However, some reactant constituents in the process gases maydeposit at low temperatures using only thermal energy or other energysources. Hence, the invention encompasses reactor designs using anyenergy source including either thermal heating, RF plasma, or the like.

ALD reactor 400 is illustrated as a single wafer reactor, but it shouldbe understood that the invention is applicable to batch reactors.

Furthermore, ALD reactor 400 includes associated control apparatus (notshown) for detecting, measuring and controlling process conditionswithin ALD reactor 400. Associated control apparatus include, asexamples, temperature sensors, pressure transducers, flow meters andcontrol valves. Associated control apparatus further include otherdevices suitable for the detection, measurement and control of thevarious process conditions described herein.

One of ordinary skill in the art will comprehend other suitable reactorsfor practicing the invention described in this application, for examplethe reactors described in U.S. Pat. Nos. 5,879,459 and 6,305,314, hereinincorporated by reference.

FIG. 5 represents an ALD system 500 suitable for practicing theinvention. ALD system 500 contains the ALD reactor 400 and a controlsystem 510. ALD reactor 400 and control system 510 are in communicationsuch that process information is passed from ALD reactor 400 to controlsystem 510 through communication line 520, and process controlinformation is passed from control system 510 to ALD reactor 400 throughcommunication line 530. It is noted that communication lines 520 and 530may represent only one physical line, in which communications arebidirectional.

The control system 510 includes, integrally or separable therefrom, amachine readable media 535 which contains instructions for performingthe present invention. Media 535 may be an electrical, magnetic,optical, mechanical, etc. storage device that stores instructions thatare read by control system 510. Such storage devices include magneticdisks and tape, optical disks, computer memory, etc. Control system 510may also include a processor (not shown) for issuing instructions tocontrol reactor 400 based upon instructions read from machine readablemedia 535.

Memory Devices

FIG. 6 is a simplified block diagram of a memory device 600 according toone embodiment of the invention. The memory device 600 includes an arrayof memory cells 602, address decoder 604, row access circuitry 606,column access circuitry 608, control circuitry 610, and Input/Outputcircuit 612. The memory is operably coupled to an externalmicroprocessor 614, or memory controller for memory accessing. Thememory device 600 receives control signals from the processor 614, suchas WE*, RAS* and CAS* signals. The memory device 600 stores data whichis accessed via I/O lines. It will be appreciated by those skilled inthe art that additional circuitry and control signals can be provided,and that the memory device of FIG. 6 has been simplified to help focuson the invention. At least one of the memory cells or associatedcircuitry has an integrated circuit structure or element in accordancewith the present invention, e.g., a metal oxide layer formed accordingto the present invention.

It will be understood that the above description of a memory device isintended to provide a general understanding of the memory and is not acomplete description of all the elements and features of a specific typeof memory, such as DRAM (Dynamic Random Access Memory). Further, theinvention is equally applicable to any size and type of memory circuitand is not intended to be limited to the DRAM described above. Otheralternative types of devices include SRAM (Static Random Access Memory)or Flash memories. Additionally, the DRAM could be a synchronous DRAMcommonly referred to as SGRAM (Synchronous Graphics Random AccessMemory), SDRAM (Synchronous Dynamic Random Access Memory), SDRAM II, andDDR SDRAM (Double Data Rate SDRAM), as well as Synchlink or Rambus DRAMsand other emerging DRAM technologies.

Semiconductor Dies

With reference to FIG. 7, for one embodiment, a semiconductor die 710 isproduced from a wafer 700. A die 710 is an individual pattern, typicallyrectangular, on a substrate or wafer 700 that contains circuitry, orintegrated circuit devices, to perform a specific function. Asemiconductor wafer 700 will typically contain a repeated pattern ofsuch dies 710 containing the same functionality. Die 710 containscircuitry for the inventive memory device, as discussed above. Die 710may further contain additional circuitry to extend to such complexdevices as a monolithic processor with multiple functionality. Die 710is typically packaged in a protective casing (not shown) with leadsextending therefrom (not shown) providing access to the circuitry of thedie for unilateral or bilateral communication and control. Each die 710includes at least one ALD deposited and converted layer, e.g., a metaloxide, according to the present invention.

Circuit Modules

As shown in FIG. 8, two or more dies 710 may be combined, with orwithout protective casing, into a circuit module 800 to enhance orextend the functionality of an individual die 710. Circuit module 800may be a combination of dies 710 representing a variety of functions, ora combination of dies 710 containing the same functionality. One or moredies 710 of circuit module 800 contain at least one ALD deposited andconverted layer, e.g., a metal oxide, in accordance with the presentinvention.

Some examples of a circuit module include memory modules, devicedrivers, power modules, communication modems, processor modules andapplication-specific modules, and may include multilayer, multichipmodules. Circuit module 800 may be a subcomponent of a variety ofelectronic systems, such as a clock, a television, a cell phone, apersonal computer, an automobile, an industrial control system, anaircraft and others. Circuit module 800 will have a variety of leads 810extending therefrom and coupled to the dies 710 providing unilateral orbilateral communication and control.

FIG. 9 shows one embodiment of a circuit module as memory module 900.Memory module 900 contains multiple memory devices 910 contained onsupport 915, the number generally depending upon the desired bus widthand the desire for parity. Memory module 900 accepts a command signalfrom an external controller (not shown) on a command link 920 andprovides for data input and data output on data links 930. The commandlink 920 and data links 930 are connected to leads 940 extending fromthe support 915. Leads 940 are shown for conceptual purposes and are notlimited to the positions shown in FIG. 9. At least one of the memorydevices 910 contains a ALD deposited and converted layer, e.g., a metaloxide, according to the present invention.

Electronic Systems

FIG. 10 shows one embodiment of an electronic system 1000 containing oneor more circuit modules 800. Electronic system 1000 generally contains auser interface 1010. User interface 1010 provides a user of theelectronic system 1000 with some form of control or observation of theresults of the electronic system 1000. Some examples of user interface1010 include the keyboard, pointing device, monitor or printer of apersonal computer; the tuning dial, display or speakers of a radio; theignition switch, gauges or gas pedal of an automobile; and the cardreader, keypad, display or currency dispenser of an automated tellermachine, or other human-machine interfaces. User interface 1010 mayfurther describe access ports provided to electronic system 1000. Accessports are used to connect an electronic system to the more tangible userinterface components previously exemplified. One or more of the circuitmodules 800 may be a processor providing some form of manipulation,control or direction of inputs from or outputs to user interface 1010,or of other information either preprogrammed into, or otherwise providedto, electronic system 1000. As will be apparent from the lists ofexamples previously given, electronic system 1000 will often beassociated with certain mechanical components (not shown) in addition tocircuit modules 800 and user interface 1010. It will be appreciated thatthe one or more circuit modules 800 in electronic system 1000 can bereplaced by a single integrated circuit. Furthermore, electronic system1000 may be a subcomponent of a larger electronic system. It will alsobe appreciated that at least one of the memory modules 800 contains aALD deposited and converted layer, e.g., a metal oxide, according to thepresent invention.

FIG. 11 shows one embodiment of an electronic system as memory system1100. Memory system 1100 contains one or more memory modules 900 and amemory controller 1110. The memory modules 900 each contain one or morememory devices 910. At least one of memory devices 910 contain ALDdeposited and converted layer, e.g., a metal oxide, according to thepresent invention. Memory controller 1110 provides and controls abidirectional interface between memory system 1100 and an externalsystem bus 1120. Memory system 1100 accepts a command signal from theexternal bus 1120 and relays it to the one or more memory modules 900 ona command link 1130. Memory system 1100 provides for data input and dataoutput between the one or more memory modules 900 and external systembus 1120 on data links 1140.

FIG. 12 shows a further embodiment of an electronic system as a computersystem 1200. Computer system 1200 contains a processor 1210 and a memorysystem 1100 housed in a computer unit 1205. Computer system 1200 is butone example of an electronic system containing another electronicsystem, i.e., memory system 900, as a subcomponent. Computer system 1200optionally contains user interface components. Depicted in FIG. 12 are akeyboard 1220, a pointing device 1230, a monitor 1240, a printer 1250and a bulk storage device 1260. It will be appreciated that othercomponents are often associated with computer system 1200 such asmodems, device driver cards, additional storage devices, etc. It willfurther be appreciated that the processor 1210 and memory system 1100 ofcomputer system 1200 can be incorporated on a single integrated circuit.Such single package processing units reduce the communication timebetween the processor and the memory circuit. It will be appreciatedthat at least one of the processor 1210 and memory system 1100 containsa ALD deposited and converted layer, e.g., a metal oxide, according tothe present invention.

While the above described embodiments describe first injecting theprecursor gas and then injecting the reactant gas, it will be understoodthat it is within the scope of the present invention to first inject thereactant gas such that it saturates the volume adjacent the substrateand then inject the precursor. The precursor will enter the volume andreact with the already present reactant gas and form a film on thesubstrate. The thus formed film is then converted according to theteachings of the present invention.

The above description described forming compounds, such as metal oxides,by ALD depositing a first monolayer, e.g., metal layer, on a substrateand/or a prior layer and then converting, e.g., oxidizing the metallayer to form a metal oxide. The present invention is also applicable toforming other elemental layers in an integrated circuit. For example, alayer is deposited using ALD and then the layer is nitrided. Thus, thelayer is now a nitride layer. The process is repeated until the nitridelayer has the desired thickness.

In another embodiment of the present invention, the layer is subjectedto boron and thus becomes a boride layer. The above described steps areperformed with the boron replacing the oxygen.

In another embodiment of the present invention, the layer is subjectedto carbon and thus becomes a carbide layer. The above described stepsare performed with the carbon replacing the oxygen.

In another embodiment of the present invention, the layer is subjectedto fluorine and thus becomes a fluoride layer. The above described stepsare performed with the fluorine replacing the oxygen.

In another embodiment of the present invention, the layer is subjectedto phosphorus and thus becomes a phosphide layer. The above describedsteps are performed with the phosphorus replacing the oxygen.

The above description sets forth embodiments of the present inventionthat atomic layer deposit a single element, then subject it to a furtherelement to convert the single element layer to an oxide, carbide,nitride, boride, fluoride, or phosphide two element layer. Embodimentsof the present invention further provide for multiple element layer tobe oxided or subjected to other elements for conversion as describedherein. Accordingly, the present invention produces mixed phase films.In an embodiment, the mixed phase films include more than one baseelement. The first element is deposited using ALD in an ALD layer,monolayer or atomic layer. It is then converted according to theteachings of the present invention. A second element is deposited usingALD in a monolayer or atomic layer. The second element layer is thenconverted according to the teachings of the present invention. In anembodiment, the first or second element is an alloy of a metal.Consequently, mixed element film is formed by sequentially depositingand converting the first element and the subsequent element(s). It willbe appreciated that the present method is adaptable to higher orders ofelements in the film, wherein a third element is deposited andconverted, . . . and an nth element is deposited and converted.

An example of such an ALD layer that is converted according to theteachings of the present invention include, but are not limited to,titanium and silicon in the base film. One embodiment would be formed bydepositing both titanium and silicon by ALD then converting one or bothaccording to the teachings of the present invention to form TiO₂SiN_(x).Titanium is deposited in an ALD layer, such as a monolayer, using ALDand then converted according to the teachings herein. Silicon isdeposited and then converted either before or after the titanium.Accordingly, the film that is formed alternates depositing andconverting the titanium and the silicon.

An embodiment according to the teachings of the present inventionincludes depositing titanium and silicon by ALD and then converting bothelements with oxygen to form TiO_(x)SiO_(x). The titanium is firstdeposited, then oxidized. The silicon is then deposited, then convertedusing oxygen. In a further embodiment, the titanium and silicon are bothdeposited by ALD, then both converted by oxidizing the titanium andsilicon. In a further embodiment, either the TiO_(x) or SiO_(x) isdeposited according to ALD and the other of the TiO_(x) or SiO_(x) isdeposited by ALD and then converted according to the teachings of thepresent invention.

An embodiment according to the teachings of the present inventionincludes depositing titanium by ALD and then converting the titaniumusing both oxygen and nitrogen to form a TiO_(x)TiN layer. In a furtherembodiment, either the TiO_(x) or TiN is deposited according to ALD andthe other of the TiO_(x) or TiN is deposited by ALD and then convertedaccording to the teachings of the present invention.

An embodiment according to the teachings of the present inventionincludes depositing silicon by ALD and then converting the silicon usingboth oxygen and nitrogen to form a SiO_(x)SiN layer. In a furtherembodiment, either the SiN or SiO_(x) is deposited according to ALD andthe other of the SiN or SiO_(x) is deposited by ALD and then convertedaccording to the teachings of the present invention.

An embodiment according to the teachings of the present inventionincludes depositing tantalum and silicon by ALD and converting tantalumwith nitrogen to form TaNSi. The tantalum is deposited, then convertedwith nitrogen. The silicon is deposited by ALD. In a further embodiment,the present invention forms TaNTaSi.

An embodiment according to the teachings of the present inventionincludes depositing aluminum and titanium by ALD and then convertingboth elements with oxygen to form AlO₃TiO₂. The titanium is firstdeposited, then oxidized. The aluminum is then deposited, then convertedusing oxygen. In a further embodiment, the titanium and aluminum areboth deposited by ALD, then both converted by oxidizing the titanium andaluminum. In a further embodiment, either the TiO₂ or AlO₃ is depositedaccording to ALD and the other of the TiO₂ or AlO₃ is deposited by ALDand then converted according to the teachings of the present invention.

The present invention includes methods of forming alloys or mixedelement films and converting the alloy or mixed element films accordingto the teachings of the present invention. Some of the above embodimentdescribe specific elements that are deposited and converted or depositedin combination with elements that are converted according to theteachings of the present invention. It will be recognized that the orderand methods described in conjunction with these specific elements areadaptable to other elements that are used to form layers in integratedcircuits.

CONCLUSION

Thus, the present invention provides novel structures and methods forfabrication of thin films on substrates. The novel fabrication method ofthe present invention forms a first layer of a single element by ALD andthen converts the first layer to a second layer having two constituentelements. The first layer is formed by atomic layer deposition and thenconverted. In an embodiment, each first layer produced during an atomiclayer deposition is converted before a subsequent first layer isdeposited on the prior converted sub-layer. In an embodiment, conversionis oxidation and the first layer is a metal. In an embodiment, eachmetal sub-layer produced during an atomic layer deposition is oxidizedbefore a subsequent metal sub-layer is deposited on the prior oxidizedmetal sub-layer. Accordingly, each sub-layer is formed at a molecularlevel by atomic layer deposition and thus has a high quality. Qualityincludes low impurity and low defects. Each sub-layer is then oxidized.Accordingly, the oxidation is throughout the sub-layer and preventsnon-oxidized areas in the sub-layer. The process is then repeated tountil the oxidized sub-layers produce a film or layer that has thedesired thickness.

The present invention includes any other applications in which the abovestructures and fabrication methods are used. The scope of the inventionshould be determined with reference to the appended claims, along withthe full scope of equivalents to which such claims are entitled.

1. A semiconductor device, comprising: a substrate; and an atomic layerdeposition first layer deposited on the substrate, wherein the firstlayer is deposited by sequentially pulsing a precursor gas and areactant into a reaction chamber, and wherein the precursor gas andreactant react to deposit the first layer on the substrate, the firstlayer including a material A, and wherein the first layer is convertedto a second layer by a converting gas, the second layer includingmaterial B, and wherein the second layer forms a material A_(x) B_(y),where x is the number of atomic bonds associated with the material A andy is the number of atomic bonds associated with the material B, andwherein the material B comprises at least one of carbon, boron andfluorine.
 2. The semiconductor device according to claim 1, wherein thematerial A is an atomic layer deposition metal.
 3. The semiconductordevice according to claim 2, wherein the second layer is a dielectric.4. The semiconductor device according to claim 3, wherein at least oneof the first and the second metal layers include at least one oftitanium, tantalum and aluminum.
 5. The semiconductor device of claim 1,wherein the second layer comprises at least one of a carbide, a borideand a fluoride.
 6. The semiconductor device of claim 4, wherein thesecond layer comprises at least one of carbide, a boride and a fluoride.7. The semiconductor device of claim 1, wherein the second layercomprises carbon and boron, or carbon and fluoride, or boron andfluoride.
 8. The semiconductor device of claim 3, wherein the secondlayer comprises a phosphide.
 9. The semiconductor device of claim 4,wherein the second layer comprises a two element layer including acarbide, a nitride, a boride, a fluoride, or a phosphide.